Sensorless Control of IPMSM Drives Using a Pseudo-Random Phase-Switching Fixed-Frequency Signal Injection Scheme

The conventional high-frequency (HF) voltage injection method can accurately extract rotor position for interior permanent magnet synchronous motor (IPMSM) drives at low and zero speed ranges. However, the fixed injection frequency will produce a loud audible noise. To solve this problem, a pseudo-random phase-switching fixed-frequency (PRPSFF) signal injection method is proposed in this paper. Based on the principle of phase selection for the PRPSFF injection scheme, the dc bias problem in the induced HF current can be diminished by setting a limitation in the injected voltage. Then a corresponding signal processing method is investigated to deal with the signal delay in the HF current extraction. Besides, the current power spectra density (PSD) for PRPSFF injection is analyzed, and a comparison between PRPSFF and the pseudo-random frequency-switching fixed-phase (PRFSFP) injection schemes is also introduced. The results show that the discrete harmonic spectrum in current PSD can be offset, and the continuous spectrum is smoother than that of PRFSFP injection. Finally, the effectiveness of the sensorless control method is verified by experiments on a 2.2-kW IPMSM drive platform.